Scripting Debug Sessions: Python for GDB Remote Serial Protocol

pyrsp-scripted-gdb

Are you tired of hammering out the same commands over and over again in GDB? If not, we highly encourage you take more advantage of The GNU Project Debugger, which is a fantastic way to poke around inside your microcontrollers while they’re running a program.

Back to the matter at hand. [Stef] put together a Python program that leverages GDB’s Remote Serial Protocol. He calls it pyrsp and the talk he recently gave about it can be seen below.

The core feature is the ability to add a callback in your C code that triggers the Python script. Think of this a little bit like a print statement, except you have so much more power since it’s Python and GDB doing the “printing”. Anything that can be done at a breakpoint in GDB can now be executed automatically. So if you need to check a group of registers at every loop execution for hundreds of loops your wrists are going to thank you. Better yet, you can use Python to do the sanity checks automatically, continuing when the data is good and alerting you when it’s not. Neat!

[Read more...]

Lulzbot & Lime Green Begonias

Lulzbot, or more specifically Aleph Objects, had a booth at Maker Faire this year, and unlike a lot of other 3D printer manufacturers they’re not afraid to show off what they currently have in development. The latest is code-named Begonia, although when it makes it to production it will probably be called the Lulzbot Mini. It’s a smaller version of their huge Taz 3D printer that trades build volume for a lower price.

The Lulzbot Mini will have a 6x6x6 inch build volume, heated bed, and all the other features you would expect in its larger counterpart. One interesting feature is automated nozzle cleaning and bed leveling. At the start of every print run, the nozzle runs over a small felt pad at the back of the build plate, touches off four metal washers at each corner, and recalculates the GCode for a level print. You can check out a demo of that in the video above.

Also in the works in the Lulzbot labs is a controller panel with an SD card, display, and (I think) a touch interface. Lulzbot didn’t have a demo of this, but rest assured, we’ll post something on that when it’s released. The last time we saw Lulzbot we heard of a 3D scanner project they’re working on that will turn any physical object into an .STL file, without having to mess about in Meshlab. Development on this project is stalled, but that is a very difficult problem. Can’t fault them for that.

Oh, the price for the unannounced Lulzbot Mini? Somewhere around $1300-1400.

Cryogenic Machining: Custom Rubber Parts

Cryogenic Machining Custom Rubber Parts

Fashioning a custom, one-off rubber part for your project isn’t usually an option, but [Ben Krasnow] has an alternative to injection molding and casting: machining frozen rubber.

As [Ben] points out, you can’t exactly pop a sheet of rubber on your mill and CNC the needed shape; the bit will push the material around rather than cut it. Freezing the rubber first, however, allows you to carve into the now-hardened material.

His initial setup consisted of a sheet of aluminum with water drizzled on top, a square of neoprene placed on the water, and a steady stream of -60 to -80C alcohol flowing directly onto the rubber. The water underneath freezes, holding the neoprene in place. This proved problematic as the ice-clamp gives way before the milling is complete. [Ben] later adds some bolts to clamp the pieces down, allowing the milling process finish as planned.

A small plastic tray sits underneath this assembly to capture the alcohol as it runs off, feeding it back with some tubing. [Ben] recommends against a submersible aquarium pump—his initial choice—because the pump stopped working after a few minutes immersed in the chilly alcohol. An external, magnetically-driven pump solved the problem although it does require manual priming.

Stick around after the jump for the video and check out some of [Ben's] other projects, like his quest for the perfect cookie, or CT scanning a turkey.

[Read more...]

THP Semifinalist: NoteOn Smartpen

PCB of the NoteOn Smartpen showing components

There are a ton of apps out there for taking notes and recording ideas, but sometimes the humble pen is best. However, if you have the tendency to lose, crumple, or spill caffeinated beverages on your pen and paper notes, having a digital copy is quite nice.

The NoteOn Smartpen by [Nick] aims to digitize your writing on the fly while behaving like a normal pen. It does this by using the ST LSM9DS0TR: a 9-axis inertial measurement unit (IMU). These inertial measurements are processed by a STM32 Cortex M4F processor and stored on the internal flash memory.

To retrieve your notes, the Nordic nRF8001 Bluetooth Low Energy radio pairs the MCU with a phone or computer. The USB port is only used to charge the device, and the user interface is a single button and LED.

The major hardware challenge of this device is packaging it in something as small as a pen. Impressively, the board is a cheap 2 layer PCB from OSHPark. The assembled device has a 10 mm diameter, which is similar to that of ‘dumb’ pens.

The NoteOn doesn’t require special paper, and relies only on inertial measurements to reconstruct writing. With the hardware working, [Nick] is now tackling the firmware that will make the device usable.

SpaceWrencherThe project featured in this post is a quarterfinalist in The Hackaday Prize.

A Water Activated Flashlight?

Water powered flash light

We’ve all seen lemon batteries or potato clocks, but have you ever seen a water activated battery?

[Nathan Stubblefield] was an American inventor (born 1860) who never got quite as much recognition as some of the other great inventors of the time, [Tesla, Bell, Edison etc] — though he did demonstrate some very interesting wireless telephony technology. In addition to dabbling with invisible radio waves, [Stubblefield] filed a patent for something called an Earth Battery, which makes use of two coils of dissimilar materials (a voltaic couple) submerged in water (or moist earth). As you can imagine, it wasn’t overly effective, nor efficient by any means — but it worked.

[Lasersaber] has been playing around with the “Stubblefield Coil” recently, and designed a working flashlight using the theory. He designed a 3D printed coil holder which allows you to easily wrap copper and magnesium strips around it to create the coil. Three of these cells go together in series to produce your water battery (and handle of the flashlight).

[Read more...]

A Li-ion Battery Charging Guide

Li-ion Battery Charging

Although [pinomelean's] Lithium-ion battery guide sounds like the topic is a bit specific, you’ll find a number of rechargeable battery basics discussed at length. Don’t know what a C-rate is? Pfffft. Roll up those sleeves and let’s dive into some theory.

As if you needed a reminder, many lithium battery types are prone to outbursts if mishandled: a proper charging technique is essential. [pinomelean] provides a detailed breakdown of the typical stages involved in a charge cycle and offers some tips on the advantages to lower voltage thresholds before turning his attention to the practical side: designing your own charger circuit from scratch.

The circuit itself is based around a handful of LM324 op-amps, creating a current and voltage-limited power supply. Voltage limits to 4.2V, and current is adjustable: from 160mA to 1600mA. This charger may take a few hours to juice up your batteries, but it does so safely, and [pinomelean's] step-by-step description of the device helps illustrate exactly how the process works.

[Thanks mansalvo]

Hackaday Links: September 21, 2014

hackaday-links-chain

Obviously the best way to show you’ve pwned a piece of hardware is to run Doom on it. This time around it’s not just a hardware hack but a security hack. [Michael Jordan] demonstrates a network vulnerability on a Canon printer by making it run Doom. [Thanks to all who sent this tip to us]

Fans of the photo-resist method of PCB etching will appreciate this Bromograph built from an old all-in-one-printer. When gutted, the body of the printer makes a nice enclosure for four UV Lamps. The treated copper clad goes face-down on the scanner glass with the printed transparency between the two. [Michele's] early testing shows really great results.

[Tom] sent in a link to this video biography of the rLab hackerspace. It shows off the space and its members but also tells the story of a tight-knit community. We enjoyed hearing that almost everything in the space is salvaged and repaired; a great way to acquire equipment on a tight budget while also building the skills of the members.

The bulbs in projectors can be quite expensive to replace. This hack adds an RC filter to the bulb and claims to greatly extend its life. Does this really work and why isn’t it built into the projector?

[Steve Maher] built a GRBL board that is the same form-factor as a DB25 connector housing. It’s basically an Arduino derivative that includes a USB connection, a separate jack for STOP and CYCLE START switches. If you’re not familiar, GRBL is an open source project that lets your drive parallel-port-based hardware with a machine that doesn’t have a parallel port.

Finally, have you heard of the ZofzPCB program before? It’s a way to visualize your gerber files in order to perform a final sanity check before sending your deign off for fabrication. [Thanks Boldport]

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